Sometimes, when I have a pretty large army (ie all 9 slots occupied) and I want to cast the same spell on multiple units, I need to open the spellbook, select the spell, select the army, select the unit to cast it on, and repeat this process. Perhaps it would be better if we could select multiple units in the army to cast the spell, so that several times that mana would be deducted, but I don't need to go through the spellbook --> select army --> select unit process so many times.

I'm not sure if this is moddable, I have a hunch it isn't.